What topic is not included in the study in the study of physical geology

Physical geology is often defined as the study of the rock types and their constituent minerals, including soil and also how they have formed and modified in the geological history. It also includes the study of earthquakes, volcanoes and their formation. Weathering, erosion of rocks and the factors responsible for this processes are also studied in this field.

In simple terms, this field of geology deals with the features and the geological processes that occurs on the surface of the earth.

The study of physical geology does not include the mantle and core. It also does not include the factors associated with them, for their formation.  

This mantle and core are classified in the field of geophysics, that describes the interior of the earth.

Epigenetic changes cannot be explained by DNA structure, but genetic changes can.

Explanation:

Epigenetics can be defined as any heritable phenotypic change that does not involve an alteration in the DNA sequence. Epigenetic mechanisms include DNA methylation, histone modifications (e.g., histone acetylation, histone methylation, etc) and regulatory non-coding RNAs (ncRNAs) pathways such as, for example, long non-coding RNA (lncRNA) pathways, small interfering RNA (siRNA) pathways, microRNA (miRNA) pathways, etc. These epigenetic mechanisms work together to modulate gene expression patterns by activating and suppressing specific genes.